1. Field of the Invention
The present invention relates to a module substrate attached to a base substrate which is utilized for a radio communication device, a measuring device, and the like, and, in particular, relates to a module substrate attached to a base substrate which is utilized for an automobile telephone or a portable telephone equipped with a small-sized communication device.
2. Description of the Related Art
Generally, an automobile telephone, a portable telephone, a personal radio device and the like are respectively equipped with small-sized communication devices which each are fabricated on a module substrate. Each of the small-sized communication devices consists of a large number of electronic parts mounted on the module substrate, and the electronic parts are electrically connected with electronic circuits put in a base substrate to utilize the electronic parts for a desired communication purpose with perfect freedom.
In this case, the module substrate is attached to the base substrate with conductive solder. Therefore, the electronic parts are electrically connected with the electronic circuits on the base substrate through the conductive solder.
In addition, in cases where the base substrate is made of glass epoxy resin, the module substrate is conventionally made of resin. Also, in cases where the base substrate is made of ceramics, the module substrate is conventionally made of resin or ceramics. However, the miniaturization of the communication device has been recently desired. Therefore, the base substrate is made of the glass epoxy resin, and the module substrate is made of the ceramics to achieve the miniaturization of the communication device.